Improvement in screw-nuts



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zulu@ UNITED STATES PATENT OEETCE.

LYMAN DERBY, OF NEW YORK, N. Y.

IMPROVEMENT IN SCREW-NUTS.

Specification forming part ofLetters Patent No. 37,435, dated January20, 1863.

ing the nut in two parts transversely of the axis ot the nut, andforming semicircular inclined planes on their matching-faces of a pitchof a greater angle than the pitch of the screw-bolt, so that, when thenut is at the Y shoulder, by applying the wrencll entirely to theoutside halfotl it, and reversing its motion for halt' a turn or less,it causes the parts to separate in consequence ot' riding` up theinclined planes, and thus changes the pitch of the two parts of the nut,and, as a matter of course, prevents the nut from unsorewin g from ott'the bolt unless the parts are readj usted; but to describe my inventionmore particularly, l will refer to the accompanying drawings, forming apart of this specification, the same. letters ot' reference whereverthey occur referring to like parts.

Figure l is aplan view of the nut as applied to the screw-bolt. Fig. 2is a face view ot' the nut. Figs. 3 and 4 are views of the minor facesof thetwo pai ts of the nut. Figs. 5 and 6 are edge views ot' theseparate parts ofthe nut, showing the pitch of the inclined planes ontheir matching-faces.

Letter A is the end of a screw-bolt, having on it the nut formed of twoparts, b and 0. These two parts are tapped in the usual way as if itwere a solid nut, and in its application to the screw in the iirstinstance in the same manner. Upon the matching-faces of the two parts ofthe nut are formed semieircular inclined planes d and e. The pitch ofthese planes are in the same direction as the pitch otl the screw-bolt,though of greater angle. The object of this is to change the pitch ofthenut by separating the parts. This is accomplished in this manner: Whenthe entire nut has been ea1ried home, the wrench is applied entirely tothe part c, and is carried back a few degrees. In doingl this theinclined planesd and e, having a pitch of a greater angle than that ot'the threads of the screw, cause the parts to separate slightly, and indoing so bind against each other, at the same time changing the pitch ofthe threads in the nut at their points of separation, and thus, inconsequence of the binding against each other and against thescrew-threads, lock ing the n nt in such a manner as to prevent it fromlosing its place on the screw bolt by any jarring or vibratory motionsit may be subjected to.

Having now described my invention and its operation, l will proceed toset forth what l claim and desire to secure by Letters Patent ot' theUnited States- The construction of a screw-nut, substantially ashereinbetore described, and operating in the manner and for the purposesset forth.

LYMAN DERBY.

Witnesses C. L. BARRITT, R. S. ROWLEY.

